This invention relates generally to the field of pressure plates used in electrical devices, and more particularly to a pressure plate which improves wire retention with a variety of wiring methods.
Electrical device manufacturers are challenged with trying to offer several wiring methods to an installer of switches and receptacles while at the same time trying to maintain a small device. Hot, neutral, and ground conductors are affixed to an electrical device using one of three methods: side wiring, back wiring, and speed wiring. In side wiring, the bare end of the conductor is wrapped a half turn around a terminal screw post and the screw head is tightened, trapping the conductor between the screw head and the terminal. The conductor must be wrapped in a clockwise direction so that tightening the screw doesn""t unwrap the conductor from the screw post. Back wiring is similar to side wiring except that a pressure plate is positioned between the screw head and the terminal. The bare end of the conductor is trapped between the pressure plate and the terminal as the screw is tightened. In speed wiring, the bare end of the conductor is inserted into a hole of the body of the switch or receptacle, where the conductor is captivated by a terminal spring arm.
Problems occur when trying to devise a pressure plate which accommodates all three types of wiring on a narrow body device.
Briefly stated, a pressure plate for an electrical device includes at least one internal standoff, at least one outboard standoff, and an anti-rotation leg. The internal and outboard standoffs prevent overtightening of the terminal screw. The anti-rotation leg preserves the orientation of the pressure plate and prevents a speed wire arm from being deformed when removing a speed wired wire from the device.
According to an embodiment of the invention, a pressure plate for an electrical device includes a flat portion, the flat portion having a hole centered therein; a first internal standoff adjacent the hole; an outboard standoff disposed at a first location on the flat portion; and an anti-rotation leg disposed at a second location on the flat portion.